The Asian Football Confederation is looking into possible disciplinary action against China's Guangzhou Evergrande after the football team's fans displayed a "political provocative" banner during an AFC Champions League match in Hong Kong.

In the closing moments of the match held at the Mong Kok Stadium, Evergrande fans unfurled a banner saying "Annihilate British dogs, extinguish Hong Kong independence poison," South China Morning Post reports.

Security at the stadium had to step in to prevent a clash between supporters of both teams when angry Eastern fans tried to confront Evergrande supporters over the banner.

"We informed the match commissioner of the banner content, and he has put it in his report to the AFC," a Hong Kong Football Association source told the newspaper.

The source added: "This banner is not allowed as they never applied to display it, but we don't know how they got away with the bag search. We will have to investigate."

The newspaper noted that AFC rules bans the display of political slogans in any form. The Chinese Super League club is likely to face a charge of improper conduct, it added.

Just hours before the match was scheduled to take place, Eastern officials doubled the number of seats allocated to the visiting Chinese team from 350 to 700 over fears that tickets set aside for the Hong Kong home team could have fallen into the hands of Evergrande fans.

The newspaper said that despite heavy security at the match and attempts to segregate the supporters, fans were seen verbally abusing each other.

The head coaches of both teams, Chan Yuen-ting from Eastern and Luiz Felipe Scolari from Evergrande did not see the banner.

Evergrande beat Eastern 6-0 in the match to lead the Champions League table with nine points.

Hong Kong faces pro-democracy protests

Over the past few years, Hong Kong has been facing pro-democracy protests. In 2014, the Umbrella movement staged an unprecedented sit-in to challenge China's decision to reject open nominations for candidates for Hong Kong's first ever elections for its chief executive in 2017.

The protesters were seeking free elections that did not involve Beijing vetting the candidates before they are allowed to stand for election. Hong Kong and Macau are 'special administrative regions' that fall under China's 'One Country, Two Systems doctrine.'

Beijing-backed Carrie Lam became the city's first female chief executive on 26 March 2017.